#### TickTock

##### Well-known member

While examine the "Full power with light throttle" issue, I have come to the conclusion that not only is the acceleration profile different between "D" and "Eco", but the units are different. It appears when you select "D" the throttle position is used to set the Torque (or acceleration if you prefer) but when you select "Eco" the throttle position sets the Power (= Torque * RPM ~= Acceleration * Speed). I have two graphs comparing the two modes when I acceleration with roughly half throttle. I kept the throttle position as steady as I could until reaching top speed.

I noticed during my tests that when in Eco mode, the energy screen traction power (kW) stayed constant for constant throttle position. Since Power = Torque*RPM (or Acceleration*Speed, if you prefer), to keep constant power, the torque must be reduced as speed increases. Since (to the first order) Torque is proportional to Current (Amps) for DC motors, we would expect Motor Amps,then, to reduce as speed increases. Indeed, this is what we find when we look at the Motor Amps profile during the Eco mode steady throttle test. I also plotted the Battery Amps to show that physics isn't violated . Since the battery voltage is relatively constant, and Power = Volts * Amps, we would expect the Battery Amps to be constant. Looking at the plot, that is what we see (except for the ramp up at the very beginning)

Now D is another story. During a test with constant throttle position in D, the Motor Amps stays constant so Torque is constant. This explains why the power steadily increases. Power is Torque*RPM so if Torque is constant and RPMs increases then Power must also increase. I plotted the battery amps again to show once more that physics isn't violated. Since the battery Voltage is relatively constant, and Power is Volts * Amps the battery Amps must ramp with speed (which, indeed it does).

You can confirm this without a Can bus logger. Just next time you have the pole position at a light, press the throttle to the desired position and hold it constant while watching the Power in the Energy Screen. If you are in D, power will steadily increase with speed. If you are in ECO, power will ramp up and then stay constant.

Note: that the two graphs are not to scale with each other (Eco mode didn't really reach top speed faster than D mode )

I noticed during my tests that when in Eco mode, the energy screen traction power (kW) stayed constant for constant throttle position. Since Power = Torque*RPM (or Acceleration*Speed, if you prefer), to keep constant power, the torque must be reduced as speed increases. Since (to the first order) Torque is proportional to Current (Amps) for DC motors, we would expect Motor Amps,then, to reduce as speed increases. Indeed, this is what we find when we look at the Motor Amps profile during the Eco mode steady throttle test. I also plotted the Battery Amps to show that physics isn't violated . Since the battery voltage is relatively constant, and Power = Volts * Amps, we would expect the Battery Amps to be constant. Looking at the plot, that is what we see (except for the ramp up at the very beginning)

Now D is another story. During a test with constant throttle position in D, the Motor Amps stays constant so Torque is constant. This explains why the power steadily increases. Power is Torque*RPM so if Torque is constant and RPMs increases then Power must also increase. I plotted the battery amps again to show once more that physics isn't violated. Since the battery Voltage is relatively constant, and Power is Volts * Amps the battery Amps must ramp with speed (which, indeed it does).

You can confirm this without a Can bus logger. Just next time you have the pole position at a light, press the throttle to the desired position and hold it constant while watching the Power in the Energy Screen. If you are in D, power will steadily increase with speed. If you are in ECO, power will ramp up and then stay constant.

Note: that the two graphs are not to scale with each other (Eco mode didn't really reach top speed faster than D mode )